An aircraft typically has one or more water stations in its cabin for selectively dispensing potable water during flight. To this end, an aircraft can have a storage tank filled with potable water and station-supply lines plumbed from the storage tank to the water station(s). The storage tank is filled between flights (i.e., when the aircraft is grounded) by connecting an external source of potable water to a ground-fill line that extends to the storage tank. Specifically, for example, ground crew connects the hose of a water service truck to the ground-fill line and allows water to flow to the storage tank.